U.S. patent application number 12/031008 was filed with the patent office on 2009-08-20 for method and apparatus for placing substrate support components.
This patent application is currently assigned to ILLINOIS TOOL WORKS INC.. Invention is credited to Steven R. Foster, Joseph A. Perault.
Application Number | 20090205569 12/031008 |
Document ID | / |
Family ID | 40475008 |
Filed Date | 2009-08-20 |
United States Patent
Application |
20090205569 |
Kind Code |
A1 |
Perault; Joseph A. ; et
al. |
August 20, 2009 |
METHOD AND APPARATUS FOR PLACING SUBSTRATE SUPPORT COMPONENTS
Abstract
An apparatus for depositing viscous material on an electronic
substrate includes a frame, a unit coupled to the frame, the unit
being configured to deposit material on the electronic substrate,
and a substrate support assembly coupled to the frame. The
substrate support assembly is configured to support the electronic
substrate. The substrate support assembly includes a plurality of
support elements, a table coupled to the frame, the table having a
support surface to support at least one support element of the
plurality of support elements, a placement head configured to
releasably secure the at least one support element, and a transport
device coupled to the frame and the placement head. The transport
device is configured to move the placement head relative to the
table in both X and Y directions to place the at least one support
element on the support surface of the table in a predetermined
position. The apparatus further includes an imaging system coupled
to the frame and a controller coupled to the imaging system. The
imaging system is configured to capture images of the support
surface of the table. The controller is configured to verify
whether the at least one support element is placed on the
predetermined position on the support surface of the table based on
images captured by the imaging system. Other embodiments of the
apparatus and related methods are further disclosed.
Inventors: |
Perault; Joseph A.; (Natick,
MA) ; Foster; Steven R.; (Norfolk, MA) |
Correspondence
Address: |
LANDO & ANASTASI, LLP
ONE MAIN STREET, SUITE 1100
CAMBRIDGE
MA
02142
US
|
Assignee: |
ILLINOIS TOOL WORKS INC.
Glenview
IL
|
Family ID: |
40475008 |
Appl. No.: |
12/031008 |
Filed: |
February 14, 2008 |
Current U.S.
Class: |
118/713 ;
382/145 |
Current CPC
Class: |
H05K 1/0269 20130101;
H05K 2203/0165 20130101; H05K 3/1216 20130101; H05K 13/0069
20130101; H05K 3/0008 20130101; H05K 13/0465 20130101 |
Class at
Publication: |
118/713 ;
382/145 |
International
Class: |
B05C 11/00 20060101
B05C011/00; G06K 9/00 20060101 G06K009/00 |
Claims
1. An apparatus for depositing viscous material on an electronic
substrate, the apparatus comprising: a frame; a unit coupled to the
frame, the unit being configured to deposit material on the
electronic substrate; a substrate support assembly coupled to the
frame, the substrate support assembly being configured to support
the electronic substrate, the substrate support assembly comprising
a plurality of support elements, a table coupled to the frame, the
table having a support surface to support at least one support
element of the plurality of support elements, a placement head
configured to releasably secure the at least one support element,
and a transport device coupled to the frame and the placement head,
the transport device being configured to move the placement head
relative to the table in both X and Y directions to place the at
least one support element on the support surface of the table in a
predetermined position; an imaging system coupled to the frame, the
imaging system being configured to capture images of the support
surface of the table; and a controller coupled to the imaging
system, the controller being configured to verify whether the at
least one support element is placed on the predetermined position
on the support surface of the table based on images captured by the
imaging system.
2. The apparatus of claim 1, further comprising a display coupled
to the controller, the display being configured to display a notice
to move the at least one support element when the at least one
support element is not positioned on the predetermined
position.
3. The apparatus of claim 2, wherein the at least one support
element is moved by an operator of the apparatus to the
predetermined position.
4. The apparatus of claim 2, wherein the at least one support
element is moved by the placement head and the transport device to
the predetermined position.
5. The apparatus of claim 1, wherein the substrate support assembly
further comprises a supply tray for holding the plurality of
support elements.
6. The apparatus of claim 1, wherein the at least one support
element comprises a pin.
7. The apparatus of claim 1, wherein the at least one support
element comprises a support housing having a low durometer gel
configured to support the electronic substrate.
8. A method of verifying an accurate placement of a support element
on a support surface of a table of an apparatus configured to
deposit material on an electronic substrate, the method comprising:
placing at least one support element of a plurality of support
elements on the support surface of the table in a predetermined
position; capturing an image of the at least one support element
disposed on the support surface of the table; and verifying whether
the at least one support element is placed on the predetermined
position on the support surface of the table based on the image
captured by the imaging system.
9. The method of claim 8, further comprising displaying a notice on
a display of the apparatus to move the at least one support element
when the at least one support element is not positioned on the
predetermined position.
10. The method of claim 9, further comprising moving the at least
one support element on the predetermined position in response to
receiving the notice.
11. The method of claim 10, wherein moving the support element is
performed by an operator of the apparatus.
12. The method of claim 10, wherein moving the support element is
performed by a placement tool of the apparatus.
13. The method of claim 8, wherein placing at least one support
element comprises manually placing the at least one support element
on a side of the table, and moving the at least one support element
with a placement tool of the apparatus to the predetermined
position.
14. The method of claim 13, wherein manually placing at least one
support element comprises placing a predetermined number of support
elements, and wherein the method further comprises counting the
support elements to verify whether the number of support elements
equals the predetermined number.
15. A computer readable medium having stored thereon sequences of
instruction including instructions that will cause a processor to:
place at least one support element of a plurality of support
elements in a predetermined position on a support surface of a
table of an apparatus to perform an operation on an electronic
substrate; capture an image of the at least one support element
disposed on the support surface of the table; and verify whether
the at least one support element is placed on the predetermined
position on the support surface of the table based on images
captured by the imaging system.
16. The computer readable medium of claim 15, wherein the
instructions will cause the processor to further display a notice
on a display to an operator of the apparatus to move the at least
one support element when the at least one support element is not
positioned on the predetermined position.
17. The computer readable medium of claim 16, wherein the
instructions will cause the processor to further move the at least
one support element on the predetermined position in response to
receiving the notice.
18. The computer readable medium of claim 17, wherein moving the
support element is performed by the operator.
19. The computer readable medium of claim 17, wherein moving the
support element is performed by a placement tool of the
apparatus.
20. An apparatus for depositing viscous material on an electronic
substrate, the apparatus comprising: a frame; a unit coupled to the
frame, the unit being configured to deposit material on the
electronic substrate; a substrate support assembly coupled to the
frame, the substrate support assembly being configured to support
an electronic substrate in a print position, the substrate support
assembly comprising a plurality of support elements, a table
coupled to the frame and having a support surface to support at
least one support element of the plurality of support elements, a
placement head configured to releasably secure the at least one
support element, a transport device coupled to the frame and the
placement head to move the placement head relative to the table in
both X and Y directions to place the at least one support element
on the support surface of the table, and a template configured to
be placed on the table, the template having at least one marking
corresponding to a predetermined position for placing the at least
one support element.
21. The apparatus of claim 20, further comprising an imaging system
coupled to the frame, the imaging system being configured to
capture images of the support surface of the table.
22. The apparatus of claim 21, further comprising a controller
coupled to the imaging system, the controller being configured to
verify whether the at least one support element is placed on the
predetermined position on the support surface of the table based on
images captured by the imaging system.
23. The apparatus of claim 22, further comprising a display coupled
to the controller, the display being configured to display a notice
to move the at least one support element when the at least one
support element is not positioned on the predetermined
position.
24. The apparatus of claim 23, wherein the at least one support
element is moved by one of the operator and the placement head and
transport device to the predetermined position.
25. The apparatus of claim 20, wherein the substrate support
assembly further comprises a supply tray for holding the plurality
of support elements.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of Invention
[0002] The invention relates generally to methods and apparatus for
depositing viscous material, such as solder paste, onto a
substrate, such as a printed circuit board, and more particularly
to a method and apparatus for placing substrate support components,
such as support pins or flexible tooling.
[0003] 2. Discussion of Related Art
[0004] When electronic substrates, such as printed circuit boards
or printed wiring boards, are subjected to manufacturing processes,
such as stencil printing or dispensing, it is often desirable to
uniformly support the substrate across the entire lower surface so
that the entire upper surface is in the same plane. It is known to
support the substrate over a table using pins that have upper
support surfaces in the same plane. When the lower surface of the
substrate is free of components, the pins can be mounted on a grid.
When the substrate has components mounted on the bottom surface,
the pins need to be located to support portions of the lower
surface between the components mounted thereon. One way to locate
the pins is to manually place pins having support bases with
magnets on a flat upper surface of a metal support table. Another
way is described in U.S. Pat. No. 5,157,438 to Beale, which
discloses supporting such substrates by selectively raising pins
mounted in holes on a grid pattern in a housing. Yet another way is
described in U.S. Pat. No. 5,794,329 to Rossmeisl et al., which
discloses an automated pin placement system.
SUMMARY OF INVENTION
[0005] Embodiments of the invention provide improvements to stencil
support assemblies, such as those described above.
[0006] One aspect of the disclosure is directed to an apparatus for
depositing viscous material on an electronic substrate. In one
embodiment, the apparatus may comprise a frame, a unit coupled to
the frame, the unit being configured to deposit material on the
electronic substrate, and a substrate support assembly coupled to
the frame. The substrate support assembly may be configured to
support the electronic substrate. The substrate support assembly
may comprise a plurality of support elements, a table coupled to
the frame, the table having a support surface to support at least
one support element of the plurality of support elements, a
placement head configured to releasably secure the at least one
support element, and a transport device coupled to the frame and
the placement head. The transport device may be configured to move
the placement head relative to the table in both X and Y directions
to place the at least one support element on the support surface of
the table in a predetermined position. The apparatus may further
comprise an imaging system coupled to the frame and a controller
coupled to the imaging system. The imaging system may be configured
to capture images of the support surface of the table. The
controller may be configured to verify whether the at least one
support element is placed on the predetermined position on the
support surface of the table based on images captured by the
imaging system.
[0007] Embodiments of the apparatus may further comprise a display
coupled to the controller. The display may be configured to display
a notice to move the at least one support element when the at least
one support element is not positioned on the predetermined
position. The at least one support element may be moved by an
operator of the apparatus to the predetermined position. The at
least one support element may be moved by the placement head and
the transport device to the predetermined position. The substrate
support assembly may further comprise a supply tray for holding the
plurality of support elements. The at least one support element may
comprise a pin or a support housing having a low durometer gel
configured to support the electronic substrate.
[0008] Another aspect of the disclosure is directed a method of
verifying an accurate placement of a support element on a support
surface of a table of an apparatus configured to deposit material
on an electronic substrate. The method comprises placing at least
one support element of a plurality of support elements on the
support surface of the table in a predetermined position, capturing
an image of the at least one support element disposed on the
support surface of the table, and verifying whether the at least
one support element is placed on the predetermined position on the
support surface of the table based on the image captured by the
imaging system.
[0009] Embodiments of the method may further comprise displaying a
notice on a display of the apparatus to move the at least one
support element when the at least one support element is not
positioned on the predetermined position. The method may further
comprise moving the at least one support element on the
predetermined position in response to receiving the notice. The
support element may be performed by an operator of the apparatus.
Moving the support element may be performed by a placement tool of
the apparatus. Placing at least one support element may comprise
manually placing the at least one support element on a side of the
table, and moving the at least one support element with a placement
tool of the apparatus to the predetermined position. Manually
placing at least one support element may comprise placing a
predetermined number of support elements. The method may further
comprise counting the support elements to verify whether the number
of support elements equals the predetermined number.
[0010] Yet another aspect of the disclosure is directed to a
computer readable medium having stored thereon sequences of
instruction including instructions that will cause a processor to:
place at least one support element of a plurality of support
elements in a predetermined position on a support surface of a
table of an apparatus to perform an operation on an electronic
substrate; capture an image of the at least one support element
disposed on the support surface of the table; and verify whether
the at least one support element is placed on the predetermined
position on the support surface of the table based on images
captured by the imaging system.
[0011] Embodiments of the computer readable medium may embody
having the instructions causing the processor to further display a
notice on a display to an operator of the apparatus to move the at
least one support element when the at least one support element is
not positioned on the predetermined position. The instructions may
cause the processor to further move the at least one support
element on the predetermined position in response to receiving the
notice. Moving the support element may be performed by the operator
or by a placement tool of the apparatus.
[0012] A further aspect of the disclosure is directed to an
apparatus for depositing viscous material on an electronic
substrate. In a certain embodiment, the apparatus may comprise a
frame, a unit coupled to the frame, the unit being configured to
deposit material on the electronic substrate, and a substrate
support assembly coupled to the frame. The substrate support
assembly may be configured to support an electronic substrate in a
print position. The substrate support assembly may comprise a
plurality of support elements, a table coupled to the frame and
having a support surface to support at least one support element of
the plurality of support elements, a placement head configured to
releasably secure the at least one support element, a transport
device coupled to the frame and the placement head to move the
placement head relative to the table in both X and Y directions to
place the at least one support element on the support surface of
the table, and a template configured to be placed on the table. The
template may have at least one marking corresponding to a
predetermined position for placing the at least one support
element.
[0013] Embodiments of the apparatus may further comprise an imaging
system coupled to the frame. The imaging system may be configured
to capture images of the support surface of the table. The
apparatus may further comprise a controller coupled to the imaging
system. The controller may be configured to verify whether the at
least one support element is placed on the predetermined position
on the support surface of the table based on images captured by the
imaging system. The apparatus may further comprise a display
coupled to the controller. The display may be configured to display
a notice to move the at least one support element when the at least
one support element is not positioned on the predetermined
position. The at least one support element may be moved by the
operator to the predetermined position or by the placement head and
the transport device to the predetermined position. The substrate
support assembly may further comprise a supply tray for holding the
plurality of support elements.
BRIEF DESCRIPTION OF DRAWINGS
[0014] The accompanying drawings are not intended to be drawn to
scale. In the drawings, each identical or nearly identical
component that is illustrated in various figures is represented by
a like numeral. For purposes of clarity, not every component may be
labeled in every drawing. In the drawings:
[0015] FIG. 1 is a front perspective view of an apparatus of an
embodiment of the disclosure for depositing material on an
electronic substrate;
[0016] FIG. 2 is a top plan schematic view of a substrate support
assembly of an embodiment of the disclosure;
[0017] FIG. 3 is a perspective view of a tray having support
elements of the substrate support system shown in FIG. 2;
[0018] FIG. 4 is a side perspective view of a placement head and
the tray of the substrate support system shown in FIG. 2;
[0019] FIG. 5 is a view showing a screen display of an embodiment
of the disclosure;
[0020] FIG. 6 is a view showing a template of an embodiment of the
disclosure;
[0021] FIG. 7 is a view showing a template of another embodiment of
the disclosure; and
[0022] FIG. 8 is a functional block diagram showing a method for
verifying the placement of support elements on a surface of an
embodiment of the disclosure.
DETAILED DESCRIPTION
[0023] This invention is not limited in its application to the
details of construction and the arrangement of components set forth
in the following description or illustrated in the drawings. The
invention is capable of other embodiments and of being practiced or
of being carried out in various ways. Also, the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," "having," "containing," "involving," and variations
thereof herein, is meant to encompass the items listed thereafter
and equivalents thereof as well as additional items.
[0024] For purposes of illustration, embodiments of the disclosure
will now be described with reference to a stencil printer used to
print solder paste onto a printed circuit board. One skilled in the
art will appreciate, however, that embodiments of the disclosure
are not limited to applications with stencil printers, but may also
be applicable to other types of equipment used to deposit materials
onto electronic substrates. For example, the principles disclosed
herein may be applied to a dispenser used to dispense viscous
materials onto printed circuit boards. In addition, although solder
paste is referenced as being an exemplary material, other
materials, such as adhesives, epoxies, underfill materials and
encapsulant materials, may be deposited as well. Also, the terms
screen and stencil may be used interchangeably herein to describe a
device in a printer that defines a pattern to be printed onto a
substrate.
[0025] Referring now to the drawings, and more particularly to FIG.
1, there is generally indicated at 10 a stencil printer of an
embodiment of the disclosure. As shown, the stencil printer 10
includes a frame 12 that supports components of the stencil
printer. The components of the stencil printer may include, in
part, a controller 14, a display 16, a stencil 18, and a print head
assembly or print head, generally indicated at 20, configured to
apply the solder paste. As shown in FIG. 1 and described below, the
stencil and the print head may be suitably coupled or otherwise
connected to the frame 12. In one embodiment, the print head 20 may
be mounted on a print head gantry 22, which may be mounted on the
frame 12. The gantry 22 enables the print head 20 to be moved in
the y-axis direction under the control of the controller 14. As
described below in further detail, the print head 20 may be placed
over the stencil 18 and a front or rear squeegee blade of the print
head may be lowered in the z-axis direction into contact with the
stencil. The print head 20 then may be moved by means of the gantry
22 across the stencil 18 to allow printing of solder paste onto a
circuit board.
[0026] Stencil printer 10 may also include a conveyor system having
rails 24, 26 for transporting a printed circuit board (sometimes
referred to as a "printed wiring board," "substrate" or "electronic
substrate") to a print position in the stencil printer. The rails
24, 26 may be referred to herein as a "tractor feed mechanism,"
which is configured to feed, load or otherwise deliver circuit
boards to the working area of the stencil printer. The stencil
printer 10 has a support assembly 28 to support the circuit board,
which, as will be described in greater detail below, raises and
secures the circuit board so that it is stable during a print
operation. In certain embodiments, the substrate support assembly
28 may further include a particular substrate support system, e.g.,
a solid support, a plurality of pins or flexible tooling, which is
positioned beneath the circuit board when the circuit board is in
the print position. The substrate support system may be used, in
part, to support the interior regions of the circuit board to
prevent flexing or warping of the circuit board during the print
operation. Embodiments of the substrate support system will be
described in greater detail below.
[0027] In one embodiment, the print head 20 may be configured to
receive solder from a source, such as a dispenser, e.g., a solder
paste cartridge, that provides solder paste to the print head
during the print operation. Other methods of supplying solder paste
may be employed in place of the cartridge. Additionally, in a
certain embodiment, the controller 14 may be configured to use a
personal computer having a Microsoft DOS or Windows XP operating
system with application specific software to control the operation
of the stencil printer 10. The controller 14 may be networked with
a master controller that is part of a line for fabricating circuit
boards.
[0028] In one configuration, the stencil printer 10 operates as
follows. A circuit board is loaded into the stencil printer 10
using the conveyor rails 24, 26. The support assembly 28 raises and
secures the circuit board to a print position. The print head 20
then lowers the desired squeegee blade of the print head in the
z-axis direction until squeegee blade of the print head contacts
the stencil 18. The print head 20 is then moved in the y-axis
direction across the stencil 18. The print head 20 deposits solder
paste through apertures in the stencil 18 and onto the circuit
board. Once the print head has fully traversed the stencil 18, the
squeegee blade is lifted off the stencil and the circuit board is
lowered back onto the conveyor rails 24, 26. The circuit board is
released and transported from the stencil printer 10 so that a
second circuit board may be loaded into the stencil printer. To
print on the second circuit board, the other squeegee blade is
lowered in the z-axis direction into contact with the stencil and
the print head 20 is moved across the stencil 18 in the direction
opposite to that used for the first circuit board.
[0029] Still referring to FIG. 1, an imaging system 30 may be
provided for the purposes of aligning the stencil 18 with the
circuit board prior to printing and to inspect the circuit board
after printing. In one embodiment, the imaging system 30 may be
disposed between the stencil 18 and the support assembly 28 upon
which a circuit board is supported. The imaging system 30 is
coupled to an imaging gantry 32 to move the imaging system. In one
embodiment, the imaging gantry 32 may be coupled to the frame 12,
and includes a beam 34 that extends between the frame 12 to provide
back and forth movement of the imaging system 30 over the circuit
board in a y-axis direction. The imaging gantry 32 further includes
a carriage device 36, which houses the imaging system 30, and is
configured to move along the length of the beam 34 in an x-axis
direction. The construction of the imaging gantry 32 used to move
the imaging system 30 is well known in the art of solder paste
printing. The arrangement is such that the imaging system 30 may be
located at any position below the stencil 18 and above the circuit
board to capture an image of predefined areas of the circuit board
or the stencil, respectively. In other embodiments, when
positioning the imaging system outside the print position, which is
sometimes referred to as the "print nest," the imaging system may
be located above or below the stencil and the circuit board.
[0030] Exemplary platforms for performing print operations may
include and are not limited to the ACCELA.RTM. and MOMENTUM.TM.
stencil printers offered by Speedline Technologies, Inc. of
Franklin, Mass., the assignee of the present disclosure.
[0031] Turning now to FIG. 2, the support assembly 28 is
schematically illustrated to show relevant components of the
assembly to be discussed herein. Specifically, the support assembly
28 includes a table 38, which is suitably coupled to the frame 12.
The table 38 includes a top support surface 40 configured to
support a plurality of support elements that are used to support a
printed circuit board 42 when in a print position. The table 38 may
include a pair of rails 44, 46 that are configured to engage and
secure the printed circuit board 42 when performing a print
operation on the circuit board. In some embodiments, the rails 44,
46 may include clamping members (not shown), such as the clamping
members disclosed in U.S. Pat. No. 7,121,199 to Perault et al.,
which discloses a substrate supporting and clamping system. The
arrangement is such that a printed circuit board 42 is loaded onto
the table 38 by rails 24, 26 and shuttled to the print nest located
above the table 38. Rails 44, 46 may be configured to secure the
circuit board 42 in a fixed position so that a stencil printing
operation may be performed on the circuit board. After the print
operation, the circuit board 42 is unloaded by rails 24, 26. After
which, the process repeats with another circuit board being loaded
onto the table 38 by rails 24, 26 and shuttled to the print nest so
that a print operation may be performed on the circuit board.
[0032] With reference to FIGS. 2-4, in one embodiment, the
substrate support assembly 28 further includes a plurality of
support elements, such as pins, each indicated at 48, which are
supported on the top surface 40 of the table 38 in predetermined
locations to be described in particular detail below. As shown in
FIGS. 3 and 4, each pin 48 includes a cylindrical base 50 and a
tapered head 52, which is configured to support the circuit board
when placing the circuit board on top of the pin. Specifically, the
arrangement is such that the head 50 of each pin 46, which is shown
as having a flattened top portion, supports the under- or bottom
surface of the circuit board 42 at locations that are unoccupied by
components mounted thereon. Pins 48 may be placed at variable
predetermined locations on the table 38 by a pin placement head 54,
which is mounted on the carriage device 36 of the imaging gantry
32. As discussed above, the placement head 54 is movable in a first
direction (e.g., an x-axis direction) by means of the carriage
device 36 as it moves along the length of the beam 34 and in a
second direction (e.g., a y-axis direction) by means of the beam as
it moves along the length of the frame 12. In certain embodiments,
the placement head 54 is at a higher elevation than the table 38
and is movable over the rails 44, 46 of the table to engage the
pins 48.
[0033] As shown in FIGS. 2 and 3, the pins 48 are dispensed by a
supply tray 56, which is located on a tray support (not shown)
under the table 38. The supply tray 56 is rotatable about an axis
to deliver pins 48 to one of two openings, each indicated at 58,
formed in the table 38. The arrangement is such that each pin 48
may be secured by the placement head 54 through one of two openings
formed in the table for positioning by the placement head on a
predetermined location on the table 38. The placement head may
include a z-axis drive mechanism to lower the placement head so
that it may pick up a pin 48 for placement. In one embodiment, the
placement head 54 may include a vacuum system to releasably secure
the pin 48 to the placement head. In another embodiment, the
placement head 54 may include a magnetic system to secure the pin
48. Once secured, the placement head is configured to move along
the beam 34 and along the frame 12 to position the placement head
over a predetermined position on the table 38 to deposit the pin 48
on the table. The placement head 54 may include employ the z-axis
drive mechanism to lower the placement head to deposit the pin 48
on the top surface 40 of the table 38. The pin 48 may be securely
positioned on the table 38 by means of a magnet housed within the
base 50 of the pin, which provides a magnetic attraction of the pin
to the metal table. In other embodiments, a vacuum system may be
employed to secure the pins 48 on the table 38.
[0034] In other embodiments, the support elements may include a
support system disclosed in U.S. Pat. No. 7,028,391 to
Pham-Van-Diep, et al., which is assigned to the assignee of the
instant disclosure and incorporated herein by reference in its
entirety for all purposes. Specifically, the support system may
include tooling sold under the brand name Gel-Flex.RTM. by
Speedline Technologies, Inc. of Franklin, Mass. This gel-based
technology, designated 60 in FIG. 2, may include a polyurethane
elastomer gel that is enclosed within a durable membrane shell and
mounted to a magnetic base. The compressible gel material may
provide gentle compliance to delicate bottom-side components and
leads while providing firm support for the entire board
surface.
[0035] Although not shown, the stencil printer 10 may include
motors and actuators that, along with the controller 14, cause the
movement of the placement head 54 and the supply tray 56. The
stencil printer 10 may also include additional sensors beyond those
required to control accurate movement of the components described
herein. In particular, the imaging gantry 32 and the placement head
54 (by means of the carriage device 36) may be moved to precisely
position a pin 48 at any x, y coordinate location on the table to
within predetermined tolerances, so long as the location does not
cause interference with rails 44, 46 or previously placed pins. The
controller 14 may include a processor, memory for storage data and
control programs to carry out the programmed procedures described
herein. Also, with reference to FIG. 1, the display 16 may be
accompanied by interactive user inputs including a keyboard 62 and
a mouse 64 that are used to manipulate the controller 14.
[0036] It should be understood that other pin placement systems,
such as the type disclosed in U.S. Pat. No. 5,794,329 to Rossmeisl
et al., which is incorporated herein by reference for all purposes,
may be employed to move the pins to predetermined locations, and
still fall within the scope of the instant disclosure.
[0037] In certain embodiments, as described above, the operator of
the stencil printer 10 may manipulate the operation of the pin
placement system by means of the mouse 64, keyboard 62 and the
display 16 via the controller 14. Specifically, the display 16 may
be configured to show a screen display that permits the operator to
operate the pin placement system. As shown in FIG. 5, which
illustrates a screen display 70 of an embodiment of the disclosure,
the pin placement system 54 may be operated under the "Tooling" tab
72, which may be provided as one of a plurality of tabs used to
operate the stencil printer. As shown, the locations for placing
the pins may be manipulated by using an edit mode. Specifically,
the screen display 70 may include a number of buttons provided on
the left-hand side of the screen display and a display of a board
area 74 indicating the area to be occupied by a circuit board on
the table, which is centrally located on the screen display. As
shown, scales for the x-axis and y-axis coordinate axes are
adjacent to board area 74, and the origin is at the bottom
left-hand corner of board area. The display of board area 74 may
also include horizontal borders provided above and below the board
area to identify the areas at the top and bottom of the board in
which pins cannot be located because they would otherwise interfere
with the edge of rails 44, 46. The board area 74 may also include a
side borders that define areas in which pins are required not to be
placed owing to other constraints provided on the sides of the
board area 74. The size and orientation of the board area 74 may be
automatically determined in a set-up mode in which the operator
inputs information as to the size of the actual circuit board and
other information. Also shown on the board area 74 are the two
openings 58 as well as reference points and exemplary pin placement
locations.
[0038] As shown, the buttons are provided for editing the tooling
placement ("Edit Tooling Placement" button 76), verifying tooling
position ("Verify Tooling Position" button 78), placing tooling
("Place Tooling" button 80), removing tooling ("Remove Tooling"
button 82), accessing the tooling carousel ("Access Carousel"
button 84), and printing the tooling layout ("Print Tooling Layout"
86). Other buttons may also be included within the buttons. For
example, although not shown, within the edit tooling placement
feature, an "add" button, which along with the other buttons, may
be activated using the mouse and keyboard user input devices. In
certain embodiments, the "add" button may be used to activate the
add feature in which the operator adds pins to the board area by
moving the cursor to the desired location and clicking on the
location. As the cursor is moved, the x and y position coordinates
may be automatically updated on screen, which may also display the
file name, the pin count and the pin ID number. The pin count is
the total number of selected pins as shown on the board area. The
pin ID number identifies the position in the selection sequence in
which the pin was originally selected. The pin ID number may also
indicate the order in which the pins will be placed on board unless
the order is modified by the operator or the automated optimization
procedures described below. Pins can be removed from the board area
using the "Remove Tooling" button 82 to activate the remove
function either automatically or manually.
[0039] While in the edit mode, the operator may activate a display
option, which lists the coordinates of the pins in the order that
they will be placed. In addition, the operator may select an option
to have the pins sequentially appear on the board area in order in
which they will be placed on the board.
[0040] After the selected positions have been entered using the
screen displays, or by importing location information from an
external file, the operator can activate optimization modules of
the software in order to avoid collisions when moving the pins and
to reduce the time spent by the placement head in placing pins by
reducing the distances that the placement head must move during a
placement operation. Before running, the controller 14 may verify
the validity of pin coordinates by performing a boundary check
sequence to confirm that pins are not specified for placement in
areas in which pins cannot be placed owing to constraints of the
placement equipment, an overlap check to confirm that pins are not
specified for placement in overlapping areas, and a total number of
pin check to confirm that a maximum pin limit is not exceeded by
the specified pins.
[0041] The display 16 may be configured to include the "Verify
Tooling Position" button 78, which may cause pins 48 to be
sequentially shown on the board area 74 in the order in which they
will be placed on the table 38 by the placement head 54. The "Place
Tooling" button 80 may then cause the placement head 54 to begin
its placement procedure. As shown, the pins 48 may be automatically
placed on the table 38 or placed manually on the table. As the pins
48 are placed, they are displayed on the board area 74, and the
coordinates of the pins may be displayed along with the elapsed
time, the percentage placed, and the numbers that have been placed.
In certain embodiments, the operator may select to run in a
"continuous" mode in which the placement head 54 runs at full speed
to place the pins in the optimum minimum time. The operator may
also select to run in a "step" mode in which the stencil printer is
advanced one step at a time and stops, and the operator must
initiate the next step. The "step" mode permits the operator to
view the placement procedure for trouble shooting and educational
purposes.
[0042] In operation, the supply tray 56 may be loaded with pins 48
by engaging the "Access Carousel" button. It should be noted that
the supply tray 56 may sometimes be referred to herein as a
"carousel." After loading, pins 48 are delivered to the openings 58
in the table 38 by rotating the supply tray 56. Pins 48 are
sequentially secured by the placement head 54 and automatically
deposited in predetermined locations on the top surface 40 of the
table 38. Specifically, when a pin 48 is secured by the placement
head 54, the placement head is moved by the imaging gantry 32 in
the y-axis direction and by the carriage device 36 in the x-axis
direction until the pin is located above the desired position on
the table 38. The z-axis drive mechanism may be employed to lower
the pin 48 on the table 48. After placing the pin 48, the placement
head 54 may be configured to return over one of the openings 58 to
secure a new pin for placement.
[0043] After all pins 48 have been placed at the desired positions
on the table 38, the circuit board 42 is moved over the tractor
mechanism to the desired location and supported on pins by lowering
the circuit board relative to the table or by raising the table to
the circuit board. When it is desired to change the pattern of
pins, in one embodiment, the pins may be cleared from the upper
surface of the table 38 by activating the "Remove Tooling" button
82 as described above. In one embodiment, a sweeper or some other
device (not shown) may be provided and moved across the table 38 to
sweep away the pins 48 off the table. The cleared pins 48 may be
collected in a container (not shown). A sensor (not shown) may be
provided to detect the presence of container, wherein the sensor
may be further configured to detect when the container is full with
pins. In another embodiment, the placement head 54 may be employed
to remove the pins 48 and place them back into the supply tray
56.
[0044] Referring to FIGS. 6 and 7, templates 90, 92, respectively,
may be generated by the controller to place on the table when
manually placing pins on the table. FIG. 6 illustrates one pin
placement template 90 having a plurality of markings 94 designating
locations for pin placement. FIG. 7 illustrates another pin
placement template 92 also having a plurality of markings
designating locations for pin placement. The templates 90 or 92 may
be suitably secured to the table 38 (e.g., by adhesive or tape)
prior to positioning the pins 48 (or other tooling) on the markings
94.
[0045] FIG. 8 illustrates an exemplary method 100 for verifying an
accurate placement of pins on the table. As shown, the method 100
includes placing at least one pin (or other support element as
described herein) on the support surface of the table in a
predetermined position at 102. Next, an image is captured of the
pin at 104. After capturing the image, the controller verifies
whether the pin is placed on the predetermined position based on
the captured image at 106. If no movement is required, the
verification routine ends. If movement is required, a notice is
displayed on the display to move the pin when the pin is not
properly positioned at 108. In further embodiments, the pin is
moved by means of the placement head or manually to the
predetermined position at 110.
[0046] In other embodiments, the method 100 may further include
manually placing the pins on a side of the table, and moving the
pins with a placement tool of the stencil printer to the
predetermined position. In a particular embodiment, manually
placing the pins includes placing a predetermined number of pins.
The method may further include counting the pins to verify whether
the number of pins equals the predetermined number.
[0047] It should be noted that the controller 14 may be configured
to perform multiple operations. Further, the controller 14 may be
configured with a computer readable medium having stored thereon
sequences of instruction including instructions that will cause the
processor to perform multiple functions. For example, in one
embodiment, the controller 14 may be configured with a pin location
verification routine, which allows the stencil printer to verify
that a pin is in its proper position. The pin location verification
routine may be a software-implemented routine that allows the
machine to verify that the pin is in proper position. During the
operation of the stencil printer, an operator manually loading
circuit boards may disrupt the pins. A typical approach to resolve
this problem was to remove all the pins and then place them
accurately again, which may take too much time. Using the methods
disclosed herein, the imaging system, under the control of the
controller, may check the location of all of the pins to verify
whether the pins are in the proper locations. In a situation where
a pin is out of position, the stencil printer may prompt the
operator to reposition the pin and continue to monitor the pin
position and advise via the display of further repositioning needs
until it is verified that the pin is in its proper position. In
certain embodiments, the placement head may be manipulated to move
the pin and to its proper position. In other embodiments, the
operator would manually place the pins in a rough location, and the
stencil printer, by means of the imaging system and the pin
placement head, would find these pins and place them in their
proper, precise location. In addition, the stencil printer may be
configured to advise the operator by means of the display to
manually move or alter the pin position.
[0048] In one embodiment, the stencil printer operator may manually
place a predetermined number of pins in a designated location on
the table, e.g., against the top rail 44 which is temporarily
opened up to accept a larger size board. Thus, with this
embodiment, the supply tray would not be part of the pin placement
system. The stencil printer may be configured to know the storage
location of the pins, find them, and place the pins by means of the
pin placement head in proper predetermined locations, while also
verifying that an operator did not accidentally place an incorrect
amount of pins in the storage location. Accordingly, with this
embodiment, the controller 14 may be configured to determine that a
proper number of pins are supplied and that the pins are placed
accurately in predetermined locations.
[0049] As discussed above, in certain embodiments, the stencil
printer may not be equipped with the automatic pin placement system
of embodiments of this disclosure. In such configurations, the
operator may print out a paper template for pin placement, such as
the templates 90, 92 illustrated in FIGS. 6 and 7, respectively.
The controller 14 may be configured so that this feature is
imbedded in the code and the operator would only need to have a
printer to print the template to a proper scale. The arrangement is
such that pins may be placed on top of the template manually and be
left in position or adjusted manually by the verification routine.
Specifically, the imaging system 30 may be manipulated to capture
an image of the pins 48. The location of the pins 48 may be
displayed on the display 16, whereby the operator may then manually
or automatically manipulate the pins to their proper locations.
[0050] In another embodiment, the pin placement system may be
automated to mark locations on a template provided on the table or
on the table directly for manual pin placement by the operator. The
imaging gantry 32 may be configured to house a device (not shown)
for marking the table 38 for the appropriate location of a manually
placed pin. Pins may be placed on the markings and be left in
position or adjusted by the verification routine. Methods for
marking the table may include writing on the table with a
felt-tipped pen that is housed by the imaging gantry, or by using a
laser pointer to indicate the position and marking the position
manually. More complicated approaches, such as thin films that
temporarily retain writing, may also be implemented.
[0051] In one embodiment, the controller 14 may be configured to
verify whether non standard tooling is placed on the table, and
whether the non-standard tooling is properly placed. As discussed
herein, there are several types of tooling available at the time of
this disclosure. For example, support elements, such as pins, basic
support blocks and gel tooling blocks, are available in a number of
sizes, such as 2.times.2, 2.times.4 and 4.times.4, which are
well-known in the art. With this routine, the software may be
manipulated to allow for the unique nature of the particular
tooling provided, and to verify that the tooling is placed properly
on the table. The operator may be prompted to alter their placement
of these particular tooling items as well as to verify their proper
placement.
[0052] In one embodiment, instead of providing the supply tray,
which is a relatively complex mechanism for storing pins, the pins
would be placed on a shelf in front of one of the two rails 44, 46,
e.g., the front fixed rail 46 (i.e., the rail adjacent the front of
the stencil printer). The imaging system may be configured to find
the pins and the pin placement head may be configured to lift them
over the front fixed rail. Once secured by the pin placement head,
the pin may be deposited in its proper position. The pin placement
head may also be configured to return the pins to the storage shelf
after verifying that there are no pins in the locations where it
intends to store them. In one particular embodiment, the pin may
not be moved over the fixed rail. However, to achieve this
function, the controller 14 may be manipulated to have the pin
placement head lift the pin higher along a z-axis. In another
embodiment, instead of using the supply tray for storing pins, the
pins would be placed in a rack and when required, the rack of pins
may be placed between the rails. The imaging system may then be
able to obtain an image of the pins, pick up the pins with the pin
placement head, and place these pins as well as put them back in
the rack as necessary.
[0053] In a particular embodiment, data obtained from an external
resource, such as CAD data, may be utilized to define pin
locations. Specifically, raw CAD data may be digested off line and
keep out zones may be utilized for automated identification of
desired pin locations and for optimization of pin locations. In
another embodiment, the software may be configured with an
interface to obtain raw board Gerber data. The software interface
could be customized for interpretation of raw Gerber data and the
analysis of pin placement possibilities. The operator may be
prompted to enter pin placement requirements and the software may
be configured to make a recommendation on pin placement for the
operator to accept or refuse.
[0054] In one embodiment, when performing a board changeover, which
requires the tooling to be repositioned on the table, and/or
tooling to be added to or removed the table, the software may be
configured to prompt the operator for manual placement of specific
tooling devices, such as pins. This prompt may include: (1)
identifying a specific area for the tooling device by using the
imaging system; (2) marking and/or laser pointing the placement
location; and (3) verifying the placement accuracy as well as
prompting for any necessary position correction. In another
embodiment, the software may be typically configured to place pins
for new boards by working from an outward position to an inward to
avoid pin collision. This approach means that for configuration
changes, the entire table needs to be cleared of any pins, and that
all new pins need to be replaced. The software may be configured to
include pin path travel analysis capabilities to optimize pin
placement. This optimization feature may enable the pin placement
to be more rapidly converted for new products in which pins may be
added within an established grid pattern without the time consuming
reconfiguration.
[0055] In yet another embodiment, in instances where the support
tooling is insufficient to properly support the circuit board, the
circuit board will sag under the pressure of the print process. In
this particular instance, there may be bridging of excessive paste
between adjacent print features. In one embodiment, the software
may be configured to perform two-dimensional and/or
three-dimensional print analysis, and to analyze the print results
to determine whether there is insufficient tooling in specific
areas beneath the circuit board. The software may also be
configured to make recommendations to place pins in certain areas
based upon detected problem areas as well as potential areas where
a pin or other tooling device could fit. In another embodiment, the
software may be configured to utilize a closed loop squeegee to
determine if pin placement problems exist. Specifically, a closed
loop squeegee may be employed to maintain constant print pressure
regardless of variations in the top surface of the circuit board.
Large squeegee moves, which may be required to maintain a desired
squeegee pressure, may likely cause a circuit board to bow beneath
the squeegee. The software may be configured to monitor the print
pressure applied by the squeegee as well as required squeegee
z-axis motion, and use this information to provide feed back
recommendations for pin placement changes that may improve the
level of support beneath the circuit board.
[0056] In a certain embodiment, the imaging system may be employed
to determine tooling placement options. Specifically, a circuit
board may be brought into the stencil printer upside down and
scanned by the imaging system. The software may be configured to
stitch images of the bottom surface of the circuit board together
and invert the images so that the operator may see the component
layout on the bottom surface of the circuit board as if the circuit
board were transparent. The operator may then decide on where to
place the pins based on the information obtained. The software may
be further configured to store both the pin grid array and the
board picture for future reference. In another embodiment, a laser
and the imaging system may be utilized to determine tooling
placement options. For example, a circuit board may require
printing on its top surface, but is delivered to the stencil
printer with its bottom side facing upwardly, thereby exposing the
populated bottom surface. A line laser may be used in conjunction
with the imaging system to scan the circuit board. The changes in
line position may be representative of the heights of the
components populated on the bottom side of the circuit board. As
with the above embodiment, the software may be configured to stitch
images of the bottom surface of the circuit board together and
invert the images so that the operator may see the component layout
on the bottom surface of the circuit board as if the circuit board
were transparent. The software may then be configured to store both
the pin grid array and the board picture for future reference.
[0057] In a particular embodiment, the imaging system may be
employed to set the heights of the pins placed on the table. Most
often, pins having fixed pin heights are employed. Pins of an
embodiment of the disclosure may be configured to have a variable
height pin that could be adjusted and locked. The tool placement
head may include a mechanism to grip the top of the pin and hold
the pin in a fixed position while a z-axis movement takes place to
either lift the head of the pin or retract the base of the pin
thereby moving the body axially to achieve a predetermined height.
In another embodiment, a circuit board that is populated on the
bottom surface and requires printing on the topside of the circuit
board may be sent through the stencil printer with the bottom
surface facing upwardly. A line laser may be employed in
conjunction with the imaging system to scan the circuit board to
determine the height of the components. The changes in line
position may be representative of the height of the components. The
software may be configured to stitch images of the bottom surface
of the circuit board together and invert the images so that the
operator may see the component layout on the bottom surface of the
circuit board as if the circuit board were transparent. The pin
placement software may further enable the operator to select pin
locations below a device, and teach and set the heights of the pins
that are needed beneath any specific component. In yet another
embodiment, a tooling changer may be utilized with a series of
different pin grippers to make use of a wider variety of pins. The
imaging system may be used to identify pin type and choose the
appropriate gripper as necessary.
[0058] As discussed herein, the principles taught herein may be
employed in other apparatus requiring tooling to support a
substrate so that an operation may be performed on the substrate.
For example, the principles taught herein may be employed on
dispensers that are capable of dispensing a wide variety of
materials onto a substrate, such as a printed circuit board or a
semiconductor wafer.
[0059] It should be understood that embodiments of the methods and
apparatus disclosed herein may be employed to perform pin placement
operations in apparatus not having inspection systems. For example,
when utilizing Gerber data, this information may be processed and
configured by the controller to move the pin placement head to
perform pin placement operations. In one embodiment, the operator
may be prompted to enter pin placement requirements and the
software may be configured to make a recommendation on pin
placement for the operator to accept or refuse.
[0060] Having thus described several aspects of at least one
embodiment of this invention, it is to be appreciated various
alterations, modifications, and improvements will readily occur to
those skilled in the art. Such alterations, modifications, and
improvements are intended to be part of this disclosure, and are
intended to be within the spirit and scope of the invention. For
example, the parameters described herein may be modified to
accommodate different printing process requirements. Accordingly,
the foregoing description and drawings are by way of example
only.
* * * * *